Unravelling the nature of deep-marine sandstones through the linkage of seismic geomorphologies to sedimentary facies; the Hermod Fan, Norwegian North Sea - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 648

120 kilometres to the west. Examples of the stud-
ied Hermod submarine fan have also been included
in a more recent Norwegian offshore stratigraphic
lexicon (Brunstad et al ., 2009).
The approach taken here has been to apply a
combination of geophysical techniques to 3d seis-
mic data to achieve enhanced imaging of geomor-
phologies over a larger area than presented in
previous publications (i.e. Blikeng & Fugelli,
2000; Hadler-Jacobsen et al ., 2005; Brunstad et al .,
2009). The geophysical work flow has resulted in
the visualisation of the Hermod Member sand-
stone with a level of detail that is rarely docu-
mented for ancient subsurface fans. The paper
focuses on the analysis of depositional elements
( sensu Mutti & Normark, 1991) and it also docu-
ments some pronounced sediment remobilisation
structures that involve Palaeocene and Eocene
stratigraphy above the Jurassic Frøy Field. The
integration of this detailed analysis of the deposi-
tional and sand remobilisation structures with
borehole data enabled an improved understand-
ing of the distribution of this excellent hydrocar-
bon reservoir.

decreased significantly (cf. Hermod, Frigg and
Grid sandstone members in Fig. 2).
The depocentres of Tertiary basins (see e.g.
Mudge & Copestake, 1992a, 1992b; Milton & dyce,
1995; Mudge & Bujak, 1996) are roughly positioned
above the axis of the Viking Graben and local elon-
gation of sediment gravity flow deposits along the
structural trends of this buried rift system suggests
long-lived control on basin bathymetry (Fig. 1).
Pronounced relief along the western bounding
fault complex of the Viking Graben appears to have
controlled the shelf edge position and formed a
high relief shelf to basin profile that existed
throughout the Palaeocene (Hadler-Jacobsen et al .,
2005). The supply of significant amounts of sand-
stone to the deep-marine basin is likely to have
occurred primarily during periods when deltas
prograded to the structurally controlled shelf edge
(dixon & Pearce, 1995). a well-defined canyon in
the Beryl Embayment is interpreted to have formed
during maximum regression of the dornoch delta
as an incised valley that was subsequently linked
into a submarine canyon that allowed for effective
sediment transfer from shelfal/deltaic sources into
the deep basin (Erik Imsland Wathne, pers.comm.).
This canyon is inferred to be the main feeder of
sediment to the studied Hermod Member subma-
rine fan complex (Fig. 2).
Sandstone intrusions are widely distributed at
Palaeocene and Eocene level in the northern
North Sea (Huuse et al ., 2007). The intrusions
connect sandstone reservoirs that are otherwise
separated by shale and are therefore of key impor-
tance for aquifer support as well as hydrocarbon
migration and trapping. a large sandstone injec-
tion complex which is thought to originate from a
parent bed in the Hermod Formation forms the
main reservoir in the Volund Field (de Boer et al .,
2007; Szarawarska et al ., 2010) and injectites
are also important in the Greater Balder area
(Bergslien, 2002). a recent paper presented a thor-
ough analysis of injectites and Palaeocene mounds
in this area and proposed that the mounds are sec-
ondary, post-depositional structures caused by
fluid influx (Wild & Breidis, 2010). The mounds
in the Greater Balder area are of similar age and
bear many similarities to the mounds that exist
over the Frøy Field that are presented herein.
However, the Hermod Fan which is the main sub-
ject of the present study does not extend to the
Volund or Balder Fields further to the south
(Fig. 2; see also palaeogeographic maps by ahmadi
et al ., 2003 and Brunstad et al ., 2009).

GEOLOGICAL SETTING

The Viking Graben (Fig. 1) was initiated as a rift
arm in the Late Jurassic (Zanella & Coward, 2003).
The rifting failed to develop to the point of break
up and rapid thermal subsidence resulted in
marine transgression over most of the Viking
Graben by the latest Jurassic.
Continued subsidence resulted in the develop-
ment of a broad deep-marine basin, bounded by
major faults to the west that became the locus for
deposition of thick successions of coarse clastics
during episodic lowstands of relative sea-level in
the Palaeocene and Early Eocene. The most exten-
sive submarine fans are located along the western
side of the basin and the inferred denudation of
large volumes of sediments in the west may be
related to pulses of regional uplift driven by man-
tle plume activity in the North atlantic Igneous
Province (White & Lovell, 1997). The mantle
activity culminated in atlantic break up (c. 56 to
53 Ma) and frequent ash eruptions produced a
series of tuff beds which today represent an impor-
tant stratigraphic marker bed (Balder Formation,
Fig. 2). a period of rapid subsidence followed
after the break up (Nadin & Kusznir, 1995) and the
volumes of sediments supplied to deep sea fans